With the advent of digital micromirror devices (DMD devices) such as digital light processors (DLPs), there has been a desire to integrate the digital projection technology into cinematic theatres for viewing by the public at large. However, as of yet, DMDs (and DLPs in particular) have not yet progressed in native resolution capability so as to allow an acceptable image for large venues which complies with industry standards for display quality. Particularly, the Society of Motion Picture and Television Engineers (SMPTE) promulgates such standards which are well respected by the various members of the motion picture industry. One such standard applies to the display of Digital Cinema Distribution Masters (DCDMs) (digital packages which contains all of the sound, picture, and data elements needed for a show) in review rooms and theatres. A requirement of the SMPTE standard is that the number of pixels for a projected image must be at least 2048×1080 (2K×1K pixels). The standard further requires that the mesh of pixels (the device structure) must be invisible when viewed from a reference viewing distance. While many DMD/DLP projectors meet the minimum requirement regarding resolution, those same projectors cannot meet the second requirement of the standard because the proper reference viewing distance is small enough to cause visibility of the mesh of pixels. Therefore, current DMD/DLP projectors having 2K×1K resolution which may not be suitable for most commercial theatres where the viewing distance is small, such as an IMAX theatre, and where to prevent the appearance of the pixel mesh from an appropriate viewing distance, a DMD/DLP projector must have a resolution of about 4K×2K (which is not currently commercially available).
A projected two dimensional (2D) image may be enhanced with an appearance of depth by converting the projected image into a so-called three dimensional (3D) image. This, is accomplished by optically polarizing the images which are to be viewed by a viewer's left eye differently than the images which are to be viewed by a viewer's right eye. The 3D effect is perceived by the viewer when the viewer views the polarized images through the use of polarized filter lenses, commonly configured as ‘3D viewing glasses’ with a polarized filter for use with the left eye of the viewer and a differently polarized filter for use with the right eye of the viewer. When the 3D viewing glasses are used to view the 3D images, the left eye of the viewer sees only the light polarized appropriately for passage through the polarized filter associated with the left eye and the right eye of the viewer sees only the light polarized appropriately for passage through the polarized filter associated with the right eye of the viewer. The above described method of displaying 3D images is known as passive 3D viewing where the projector alternates the left eye information with the right eye information at double the typical frame rate and a screen/filter/polarizing blocker in front of the projector's lenses alternates the polarization of the projected image in such a way that the image of each eye passes through the corresponding polarizing filter of the pair of passive stereo glasses discussed above. An alternative to passive 3D viewing is active 3D viewing where each viewer wears glasses with LCD light shutters which work in synchronization with the projector so that when the projector displays the left eye image, the right eye shutter of the active stereo eyewear is closed, and vice versa. One problem with current systems for providing 3D images is that the projectionist must attach and configure an external special device to the standard projector, which is a costly and time consuming requirement which also leads to technical failure. Further, when the projectionist again desires to project only a 2D image, the special device must be manually removed or turned off. In addition, having such a device attached to the projector parallel to the projection lens surface introduces a risk that light will reflect back to the imagers from which the light originates, often causing lower picture quality in color productions and undesirable contrast ratio change in black & white productions. While there are many advanced methods of displaying 3D images, room for improvement remains.
Referring now to FIG. 1, a typical three color prism 100 is shown. Prism 100 is typically used with a three-chip digital micromirror device projector. As shown, a light beam 102 enters prism 100, and in reaction to known optical coating methods, is selectively reflected or transmitted depending on the wavelength of the light. Further, known total internal reflection techniques, such as providing a small air gap between prism 100 components, may be used to control the reflection of the divided components of light beam 100. After having been separated into three color components, each light beam 102 color component is directed to and selectively reflected out of prism 100 by a digital micromirror device. Particularly, digital micromirror device 104 reflects a blue color component of light beam 102, digital micromirror device 106 reflects a green color component of light beam 102, and digital micromirror device 108 reflects a red color component of light beam 102. Each digital micromirror device 104, 106, 108 may be individually controlled in a known manner to produce a combined color image which is projected from prism 100.
It is therefore desirable to develop an improved a projection system capable of displaying high resolution 3D images.